1. Field of the Invention
The present invention relates to spectacles for reducing glare from the headlights of oncoming traffic while driving at night.
2. Prior Art
The current popularity of SUV's and pick-up trucks, with headlights higher then is normal for typical sedans, are a hazard during driving at night. The oncoming headlights on a roadway shine directly into the eyes of the driver of a sedan. This brief intense light source causes a momentary blindness and discomfort for approximately 3-5 seconds. During that period of uncertainty the driver's view of a curve in the road ahead, or any other unlighted vehicle, object, cyclist or animal in the road before him is impaired and an accident may ensue. Often the police will attempt to attribute the cause of a rollover or accident to alcohol or drug content in the driver's blood. When subsequent measurement indicate no sign of either alcohol or drugs in the driver's blood, the accident is attributed to “unknown causes”. Yet this driver may have experienced the aforesaid temporary blindness from the glare of headlights on an oncoming vehicle. As the use of higher intensity Xenon and blue headlights become more common, the problem is increasingly in severity. It has been reported that there is an increase in ‘driver eye fixation’ on these new high intensity lights relative to the older tungsten headlights.
It is desirable to block or reduce the intensity of oncoming vehicle headlights while retaining normal viewing capability in the visual field to the right of the roadway center dividing lines and in the direction one is driving. Any form of night glasses using filter coating which covers the visual field ahead may help reduce the oncoming headlight intensity, but they also reduce the brightness of the forward driving field ahead. Any reduction in the original brightness results in a decrease in contrast sensitivity of the eye in that field. It is particularly true if the road ahead is relatively dark and brightness levels are in the order of 0.3 millilamberts. Consequently the driver is not using the full capability of his/her eyes during night driving when the driver needs them the most.
To overcome the problems associated with glare from oncoming traffic, a number of night driving glasses have been disclosed in the prior art. Examples of prior art attempts to provide night driving glasses include U.S. Pat. Nos. 5,252,997 and 6,113,233. Kelly, in U.S. Pat. No. 2,511,776, discloses a pair of spectacles having lenses wherein the upper half of each lens is translucent and the lower half transparent. An inverted “V—shaped” notch in the lower edge of the translucent portion is claimed to block light from oncoming traffic but permit viewing of the driver's lane immediately ahead of the vehicle, but it also reduces the overall brightness of the field ahead. The arrangement is also purported to block headlights from following traffic. A disadvantage of the arrangement is that due to the dimensions of the notch, it does not permit clear viewing of the road ahead to the horizon in full brightness while blocking the oncoming headlights. There is a continuing need for night driving glasses that reduce glare from oncoming headlights yet do not reduce light intensity within the field of view of the driver that is required for safe driving.